1. Field of the Invention
This invention relates to a process for extracting vitamins from plant matter and more particularly to a process of extracting vitamin E from Annatto plant matter.
2. Description of the Related Art
Vitamin E refers to a group of fat-soluble compounds that are found in plants and plant-derived matter such as, for example, vegetable oils. It is also found in some oils/fats of animal origin. Vitamin E appears to have multiple roles in human metabolism. The main biological activity of vitamin E is understood to be as a powerful antioxidant. It is also reported to reduce free radicals and inhibit the production of reactive oxygen species (ROS). Compounds of the vitamin E group play a role in the immune system, in the regulation of gene expression, in the regulation of some enzymatic activities, as an anti-carcinogenic and in other functions.
Said group comprises four tocopherol and four tocotrienol compounds which are identified by the prefixes alpha, beta, gamma and delta. Wheat germ oil, sunflower seeds and oil, safflower seeds and oil, palm oil, fish oils, soyabean seeds and oil, annatto seeds and almonds are some of the sources rich in these compounds. Some of the said sources are rich in the tocotrienols while the others contain more of the tocopherols.
The vitamin in these sources is mostly in the form of esters that are referred to herein collectively as vitamin esters. A small quantity of the vitamin is found in the form of alcohols which is referred to herein collectively as vitamin alcohols.
A generalised process for the recovery of fat-soluble vitamins (such as vitamin E) found dissolved in natural vegetable oils comprises saponifying the oil. During saponification the oil gets converted to a soap while some of the vitamin esters get converted to vitamin alcohols.
The vitamin esters and alcohols and some other compounds such as phytosterols and squalene in the oil separate out being immiscible in the soap layer. This layer is separated from the soap and is referred to herein as the semi-concentrate.
In addition to vitamin E esters and alcohols, said semi-concentrate contains esters and alcohols of other oil-soluble vitamins such as A and D. Through a process of solution partitioning the vitamin E component is isolated, purified and formulated into capsules or other forms. Before formulation, it may be dissolved in some suitable bland oil such as for example, corn oil and the solution packaged. The semi-concentrate may be concentrated and the concentrate packaged into appropriate doses.
In a variant of the above process, the concentrate is esterified. The vitamin alcohols get converted to the ester form which is then separated.
In another prior art process the original vitamin containing oil is subjected to high vacuum distillation to distill off the vitamin in the ester form. The vitamin ester distillate is subjected to purification steps and then packaged.
U.S. Pat. No. 2,380,409, to L. O. Buxton, discloses a process wherein a marine oil is contacted with a liquid aliphatic organic solvent at an elevated temperature. The extract is cooled to a low temperature at which the solution of the vitamin esters and alcohols in the solvent separates out. This solution is also referred to as the semi-concentrate. The solvent is removed from the semi-concentrate which is then contacted with a highly polar solvent that is substantially immiscible with the semi-concentrate at low temperatures.
The solution containing the polar solvent and the said esters and alcohols is cooled. The polar solvent phase containing the vitamin alcohols separates out. The non-solvent layer is the ester concentrate and contains the natural vitamin esters originally present in the oil. It is stated to be substantially free of free-fatty acids and the disagreeable odour and colouring components present in the oil. In a variant, the marine oil is directly treated with the polar solvent and the residual oil treated with the said aliphatic organic solvent to obtain the vitamin esters.
U.S. Pat. No. 7,575,767 B2, to C. Y. May, discloses a process wherein palm oil is treated with a low alkyl alcohol. An acid or alkaline catalyst is provided, which causes esterification and trans-esterification of the vitamin alcohols and esters. The vitamin alcohols get converted to esters and a part of the vitamin esters originally present in the oil gets transesterified. The esterified mass is subjected to three stages of short path vacuum distillation to give a vitamin E enriched fraction, a fraction containing the phytosterols and one containing squalene.
A similar process wherein triple distillation is adopted has been reported for extraction of vitamin E, squalene and sterols from condensates obtained during vegetable oil refining and/or the distillates obtained during the deodorisation of plant oils. The process employs bioethanol, glycerol and hydrocarbons generated in the process and does not require any external solvent of petroleum or other origin.
Processes using extraction by several different solvents such as 96% ethanol and hexane, petroleum ether, ethyl acetate, methanol and NaOH and EDTA, n-hexane and others have been reported. In one process, the solvent extraction is assisted by ultrasound inputs.
Super critical extraction with carbon-dioxide is also practised in the prior art. Other methods based on chromatography, enzyme catalysis etc are also known.
The drawbacks in the solvent extraction processes of prior art reported above are:                (i) The presence of vitamin alcohols in the vitamin product. Vitamin alcohols make the product unstable and reduce the shelf life. In some processes the product is mostly all in the form vitamin alcohols with very little of the original natural vitamin esters.        (ii) In some processes, synthetic vitamin esters are produced which come into the product. Such synthetic esters appear to have lesser efficacy than the natural vitamin esters contained in vitamin E containing oils.        (iii) Where vitamin alcohols are present in the product, the disagreeable odour factors in the oil come out into product along with the vitamin alcohols. Similarly, disagreeable taste and colouring factors also come out in the product extract.        (iv) The employment of solvents of petroleum origin.        (v) In the processes employing esterification and trans-esterification operations, the said operations are not complete and some vitamin alcohols tend to remain unconverted.        